feat: introduce wallet index for saving wallet txn

blockchain/walletIndex.go

@@ -0,0 +1,49 @@
+package blockchain
+
+import "log"
+
+type WalletTransactionIndex struct {
+	BlockHeight      int          `json:"block_height"`
+	TransactionIndex int          `json:"transaction_index"`
+	Transaction      *Transaction `json:transactions"`
+}
+
+type WalletIndex struct {
+	Transactions map[string][]*WalletTransactionIndex `json:"transactions"`
+}
+
+func NewWalletIndex() *WalletIndex {
+	return &WalletIndex{
+		Transactions: make(map[string][]*WalletTransactionIndex),
+	}
+}
+
+func (w *WalletIndex) AddTransaction(address string, blockHeight int, txIndex int, transaction *Transaction) {
+	if w.Transactions == nil {
+		w.Transactions = make(map[string][]*WalletTransactionIndex)
+	}
+
+	wti := &WalletTransactionIndex{
+		BlockHeight:      blockHeight,
+		TransactionIndex: txIndex,
+		Transaction:      transaction,
+	}
+
+	log.Printf("Adding transaction: Address=%s, BlockHeight=%d, TxIndex=%d", address, blockHeight, txIndex)
+	w.Transactions[address] = append(w.Transactions[address], wti)
+	log.Printf("Transactions for %s: %+v", address, w.Transactions[address])
+}
+
+func (w *WalletIndex) CalculateBalance(address string) int {
+	bal := 0
+
+	for _, txn := range w.Transactions[address] {
+		if txn.Transaction.From == address {
+			bal -= int(txn.Transaction.Value)
+		} else if txn.Transaction.To == address {
+			bal += int(txn.Transaction.Value)
+		}
+	}
+
+	return bal
+}